Solubility and charge inversion of complexes of DNA and basic proteins
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Updated: Jul 19, 2026

CD Spectroscopy to Study DNA-Protein Interactions
Published on: February 10, 2022
Eric Raspaud1, J Pelta, M de Frutos
1Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris Sud, 91405 Orsay Cedex, France. raspaud@lps.u-psud.fr
Abstract:
The basic proteins, protamines and histones H1, are known to condense DNA in vivo. We examine here their ability to condense and solubilize in vitro linear DNA [and a synthetic polyanion, Poly(Styrene-Sulfonate) or PSS] at low ionic concentrations by varying the charge concentration ratio. Phase separation is observed in a very narrow range of ratios for short DNA and PSS; on both sides of this range, polydisperse and charged complexes are formed. A charge inversion is detected. For long DNA chains however, a different behavior is observed: the complexes are not soluble in excess of proteins.
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